This invention relates to fixed wing aircraft, and more particularly concerns aircraft capable of vertical ascent by virtue of lift produced from air blown through slots in the upper surfaces of the wings.
Conventional aircraft generally utilize specifically contoured wings which produce lift during forward horizontal motion through the air. As air flows past the wing, a low pressure is produced on its upper surface, thereby resulting in a lifting effect.
Known heavier-than-air vehicles which can rise in air without forward motion include rocket and jet propelled aircraft wherein downwardly directed gases push the vehicle by reaction effect pursuant to Newton's third law of motion, and helicopters which utilize a large blade structure that rotates in a substantially horizontal plane. Jet propelled airplanes of VTOL design (vertical take-off and landing) are of complex design, utilizing rotating engines which exhaust downwardly for vertical lifting and descent, and exhaust rearwardly for forward motion where lift is produced by fixed wings of generally conventional design.
U.S. Pat. No. 2,946,540 describes an aircraft with enhanced lifting effect achieved by blowing air through slots along the leading edge of the wings. Such lifting improvement is caused by the Coanda Effect wherein the air emergent from the slots forms a layer that clings to the upper wing surface. In practice however, frictional interaction between the ambiant air stream and the upper surface of the wing causes separation of the air stream from the surface of the wing resulting in loss of the Coanda Effect, hence loss of lift.
U.S. Pat. No. 2,939,650 seeks to retain the Coanda Effect by inducting the boundary layer and contiguous layers through perforations in the upper surface of the wing downstream from the slot. A limitation of this approach is that the induction of air may be inadequate to keep up with the rate of formation of the boundary layers at air stream volumes and velocities required for vertical lift.
U.S. Pat. Nos. 1,979,298; 1,993,419; 2,041,795; and 2,223,744 disclose aircraft with air discharge and induction slots in the wings for control of the boundary layer with attendant improved flight performance. However, in said Patents, the volume and velocity of the discharged and inducted air is inadequate for vertical ascent.
It is accordingly an object of the present invention to provide an aircraft having fixed wings equipped with air discharge and induction slots, and associated air handling means capable of producing sufficient velocity and volume of air flow relative to said slots to enable the aircraft to ascend vertically.
It is a further object of this invention to provide an aircraft as in the foregoing object wherein the effectiveness of said slots is controllable.
It is another object of the present invention to provide an aircraft of the aforesaid nature powered by a jet engine.
It is a still further object of this invention to provide an aircraft of the aforesaid nature whose wings provide conventional lift during forward flight.
It is yet another object of the present invention to provide an aircraft of the aforesaid nature whose control surfaces, namely ailerons, flaps and elevators, can effectively control the aircraft during V/STOL and hovering flight as well as during conventional forward flight.
These objects and other objects and advantages of the invention will be apparent from the following description.